1. Field of the Invention
The present invention relates to a line coupling assembly for guiding electrical signals into a high-frequency shielded area such as a room, chamber, cabinet or the like.
2. Description of the Prior Art
In general, high-frequency devices generate disturbances in operation which make a shielding of the device necessary. Conversely, there are devices which are sensitive to external disturbances and which have to be shielded from such disturbances to function perfectly. Specifically, MR (magnetic resonance) devices need to be provided with a high-frequency shielding in order to prevent high-frequency signals generated by the MR device as disturbing signals from penetrating to the outside of the device, and also to shield the sensitive high-frequency receiving channel of the MR device from outside disturbances. If additional devices are operated within the high-frequency shielding chamber besides the MR device, then signal lines and/or power supply lines need to be led into the high-frequency chamber for these devices. Hollow conductor feed-throughs or bushings are known which are dimensioned as high-pass filters such that the lower limit frequency of the hollow conductor feed-through lies far above the operating frequency of the MR device. Light waveguides or plastic tubes, e.g. compressed air lines for pneumatic systems, can be fed through the hollow conductor feed-throughs, for example. Additionally, feed-through filters for quasi-static or low-frequency signals are known which have a very high attenuation in the region of the operating frequency of the MR device.
A sufficient shielding effect in the frequency region of interest is not always possible. For optical position measuring systems where there is cyclical firing of light-emitting diodes with a high pulse energy, for example, there is no suitable signal feed-through into the high-frequency shielding chamber. There is also no known practicable technical solution for high-frequency therapy devices which allows operation of such a device immediately next to the MR device in the high-frequency shielding chamber.
German OS 195 16 641 discloses an assembly wherein the introduction of electrical lines into a high-frequency shielding is possible without prejudicing the operation of a high-frequency device arranged inside the high-frequency shielding. An external power supply is therein separated from the assembly during the measuring operation in the high-frequency shielding chamber by means of a change-over switch, and this power supply is connected to a reference potential. The assembly is powered with electrical energy via electronic elements during this time. During the measuring pauses the assembly is connected to the external power supply.